Torque converters have been known and used in combination with automatic transmissions of automobiles for quite some time. Generally, a torque converter consists of a housing, an impeller or pump, a turbine, a stator containing a one-way clutch, and a lock-up clutch.
The impeller is hemispherical with an outer wall having inner and outer surfaces, and a plurality of vanes radially mounted to the concave inner surface of the impeller wall. The turbine is rotatably mounted within a back wall, and also contains a plurality of vanes opposite the impeller vanes. The impeller wall is welded to the converter body to form an enclosed housing for the torque converter. The stator is located between the impeller and the turbine. The impeller has an input shaft operatively connected to the engine drive shaft. The turbine has an output shaft attached to the transmission input shaft so as to rotate the output shaft of the transmission.
In use, fluid, such as oil, is added into the torque converter housing. When the engine shaft rotates the impeller, the fluid starts rotating as well. As the rotation speeds up, centrifugal forces cause the fluid to flow outward toward the impeller vanes. The impeller vanes direct the fluid towards the turbine vanes, wherein the force of the fluid causes the turbine to rotate in the same direction as the impeller. The turbine shaft rotates the transmission shaft, which causes the vehicle to begin moving. The orientation of the turbine vanes directs the fluid towards the center of the turbine, where the vanes of the stator direct the fluid back towards the impeller, and the fluid cycle is repeated. Initially, the impeller will be rotating at a much greater speed than the turbine, which results in energy loss between input from the motor and output to the transmission. However, when the vehicle reaches a higher speed (approximately 40 miles per hour), the impeller and turbine will be rotating at approximately the same speed. At this time, a lock-up clutch will mechanically connect the impeller and the turbine so that they rotate at exactly the same speed to transfer 100% of the power through the torque converter.
A lock-up clutch, such as in a Ford transmission, is installed in front of the turbine. When engaged, the clutch will rotate with and lock together the rotational speeds of the impeller and the turbine. This is called the “lock-up operation.”
The torque transferred from the engine to the transmission via the torque converter depends, in part, on the number of plates in the lock-up clutch. Conventional lock-up clutches have 1-3 plates which are forced by a piston into contact with the torque converter casing so as to couple the turbine to the impeller at the desired engine speed. Generally, the more plates in the clutch, the greater the torque transmitted from the engine to the transmission. Multiple plates, called a clutch plate pack, are set within the clutch sidewall and covered with a backing plate, which in conventional practice is welded to the inside surface of the clutch sidewall. The clutch sidewall height limits the number of plates which can be installed, and thus limits the torque transmitted through the torque converter.
Accordingly, a primary objective of the present invention is the provision of an improved lock-up clutch for a torque converter which accommodates additional clutch plates to increase torque transfer from the engine to the transmission.
Another objective of the present invention is the provision of a torque converter with a lock-up clutch, and having a sleeve mounted over the clutch sidewall so as to increase the depth of the clutch cavity, thereby allowing a clutch plate pack with more plates to be installed for increased torque capacity of the clutch.
Still another objective of the present invention is the provision of a method for increasing the torque of a torque converter having a lock-up clutch.
Yet another objective of the present invention is the provision of the method of increasing the depth of a lock-up clutch housing or cover so as to allow additional clutch plates, and thereby increase the torque of the converter.
A further objective of the present invention is the provision of a lock-up clutch for a torque converter, with a clutch cover having an extended sidewall to accommodate additional clutch packs for enhanced torque transmission from the engine.
Another objective of the present invention is a method of increasing the height of a lock-up clutch sidewall for more clutch plates to provide increased torque in a torque converter.
A further objective of the present invention is the provision of a sleeve for an improved lock-up clutch which can be economically manufactured and easily installed the clutch cover on a torque converter.
These and other objectives will become apparent from the following description of the invention.